/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.solr.search;

import java.io.IOException;

/**
 * Implementations of <code>CacheRegenerator</code> are used in autowarming to
 * populate a new cache based on an old cache. <code>regenerateItem</code> is
 * called for each item that should be inserted into the new cache.
 * <p>
 * Implementations should have a noarg constructor and be thread safe (a single
 * instance will be used for all cache autowarmings).
 * 
 * @version $Id: CacheRegenerator.java 555343 2007-07-11 17:46:25Z hossman $
 */
public interface CacheRegenerator {
	/**
	 * Regenerate an old cache item and insert it into <code>newCache</code>
	 * 
	 * @param newSearcher
	 *            the new searcher who's caches are being autowarmed
	 * @param newCache
	 *            where regenerated cache items should be stored. the target of
	 *            the autowarming
	 * @param oldCache
	 *            the old cache being used as a source for autowarming
	 * @param oldKey
	 *            the key of the old cache item to regenerate in the new cache
	 * @param oldVal
	 *            the old value of the cache item
	 * @return true to continue with autowarming, false to stop
	 */
	public boolean regenerateItem(SolrIndexSearcher newSearcher,
			SolrCache newCache, SolrCache oldCache, Object oldKey, Object oldVal)
			throws IOException;
}
